Method of conditioning superphosphate



Patented Apr. 30, 1940 2.10am msrnon or-coN moNlNG s rnos Johnson Bagood,

.Bartow,

PHAT! assignorto Flt, Southern Phosphate Oorpora'tion, Bartow, Fla..- a corporation of Delaware 1 No mm. application m 1, use,

Serial No. cum I v z M (c1. 11-) The present invention relates to the conditioning of superphosphate and to the production of a fertilizer therefrom.

A neutral fertilizer formed by mixing'ingredi- 5 cats to provide a balanced ratio of plant food. such as phosphorus, potassium, and nitrogen has long been sought. It is well-known that the phosphorous content may be supplied in the form of phosphorous pentoxide in superphosphate, but

superphosphate has undesirable properties, such as lack of drillability, and a free acid content that y seriously impairs its value as an ingredient.

It is common practice to ammoniate superphosphate by subjecting it to ammonia gas under pressure, but this process resultsin a partial reversion of the phosphorous pentoxide so that there is a loss in available phosphorous content.

Furthermore the elaborate apparatus necessary renders the process quite expensive.

;I l The herein disclosed process is not an ammoniation process although it takes advantage of the action of ammonia gas upon superphosphate to I produce an improved product.

One object of the invention is to provide an I inexpensive novel method 'of conditioning superphosphate to change its physical properties so i that it will have improved drillability.

Another object is to provide a process for producing a mixed fertilizer containing available 130 phosphorous pentoxide (PzOs) supplied by superphosphate, and which will have desirable physical properties.

Still another object is the manufacture of a neutral fertilizer.

85 Preferably in carrying out the invention a mixture of a mineral ammonium salt, such as ammonium sulfate (NHAMSOi or diammonium phosphate (NHilaflPOi and calcined phosphate is prepared. It is well-known that when calcined 40 phosphate comes into intimate contact with either of these salts, ammonia gas is evolved. Immediately upon completion of the mixture, a blanket of superphosphate is thrown over it, and allowed to stand for several hours, or preferably to overnight. After a period of standing sufficient to allow the superphosphate to absorb the evolved ammonia, the mixed fertilizer will be found'to have become conditioned, whereby it becomes easily drillable. The ammonia neutralizes the so free acid of the superphosphate and gives the very much desired neutral product.

A mixed fertilizer may be prepared by including the desired ingredients in the mix. By way of example, two thousand pounds of a fertilizer s in the ratio of eight percent available phosphorplaced. It is dry and therefore drillable.

ous pentoxide, three percent available nitrogen and five percent available potassium oxide may be prepared as follows:

From one hundred and fifty to three hundred pounds of calcined phosphate, depending upon 5 the superphosphate to be used, three hundred ,pounds of ammonium sulphate, (NHOQSO, and

two hundred pounds potassium chloride may be mixed by a rapid agitation. The agitation must be as rapid as possible to prevent the loss of ammonia evolved as a result of the mixture.

' erable way of treating the superphosphate, it is its obvious that all of the ingredients, including the superphosphate, may be mixed together-simultaneously in any suitable manner, provided that the mixing is quickly accomplished to prevent waste of ammonia, and consequent incomplete conditioning of parts of the superphosphate, the quantity of which is proportioned to the quantity of ammonia gas evolved.

Fertilizer produced in this manner is a very satisfactory product. It is completely neutral 85 and will not attack Jute sacks in which it is The ratio of the diiferent plant foods may be varied to meet different requirements.

Inasmuch as superphosphate varies as to its 0 contents of free acid, and mono-calcium and tricalcium phosphates, the amount of ammonia necessary to condition it varies with different lots. The proportions of a mix that will contain the amount of calcined phosphate necessary to drive of! enough ammonia to condition a given amount of any particular superphosphate may be easily determined by experiment as follows:

Ammonium salt and calcined phosphate are mixed, and placed in a container and immedi- 5o ately covered with a proportionate amount of superphosphate. The complete batch is allowed 'to be satisfactory; an adjustment may be made by changing the proportion of calcined phosphate. The physical qualities of a superphosphate conditioned in this manner may be varied considerably by varying the quantity of ammonia absorbed by it, and the quantity 0! ammonia evolved from a given quantity of an ammonium salt may be varied by changing the proportion of calcined phosphate with which it is mixed.

The foregoing description is for the purpose of illustration and not of limitations; and it is my intention that the invention be limited only by the appended claims or their equivalents, in which I have intended to claim broadly all inherent' novelty.

What Iciaimis:

1. The process 0! conditioning superphosphate JOHNSON HAGOOD. 

